Quality Control and Process Optimization Flashcards

A plant manager notices a process has a Cpk of 0.85. What does this indicate?

Answer: The process is not capable and may produce defects

A Cpk below 1.0 indicates the process is not capable of consistently producing parts within specification limits.

Which DMAIC phase involves identifying root causes of defects using tools like fishbone diagrams?

Answer: Analyze

The Analyze phase uses tools like fishbone (Ishikawa) diagrams, 5 Whys, and regression analysis to identify root causes.

What is the primary purpose of a Gauge R&R study?

Answer: To evaluate measurement system variation

Gauge R&R (Repeatability and Reproducibility) quantifies the variation in a measurement system due to the gauge and the operators.

In a Pareto analysis of defect types, 80% of defects come from 3 out of 15 defect categories. What should the plant manager do first?

Answer: Focus improvement resources on the 3 dominant defect categories

Pareto analysis applies the 80/20 rule, directing resources toward the vital few causes that produce most of the problems.

A control chart shows 8 consecutive points on one side of the center line. This is an example of:

Answer: A special cause signal requiring investigation

Eight consecutive points on one side of the centerline is a recognized Western Electric rule signaling a special cause that needs investigation.

Which quality cost category includes scrap, rework, and warranty returns?

Answer: Internal failure costs and external failure costs

Scrap and rework are internal failure costs, while warranty returns are external failure costs — both are failure cost categories.

What does OEE (Overall Equipment Effectiveness) measure?

Answer: The combined impact of availability, performance, and quality on productive output

OEE = Availability × Performance × Quality, providing a single metric for how effectively manufacturing equipment is utilized.